A probable volleyball game seen at the Main Administrative Area of the Punggye-ri Nuclear Test Site, taken on April 16, 2017. (Photo DigitalGlobe/38 North via Getty Images)

At a time of remarkable tensions over Pyongyang's weapons program, satellite images of North Korea appeared to capture images of multiple volleyball games being played at the country's main nuclear testing site.

The images, taken Sunday by satellite company Digitalglobe and later released by the independent North Korea monitoring project 38 North, appeared to show groups of people playing volleyball at three separate locations at the secretive nuclear facility. The images surprised analysts at 38 North, as they coincided with speculation about North Korean plans to test a nuclear weapon.

On the weekend the world held its breath in anticipation of a sixth North Korean nuclear test, staff at the Punggye-ri Nuclear Test Site were apparently playing volleyball. (Jason Aldag,Adam Taylor/The Washington Post)

Three analysts working with 38 North — Joseph S. Bermudez Jr., Jack Liu and Frank Pabian — published a note Wednesday suggesting that activity at the Punggye-ri Nuclear Test Site appeared to be slowing after two months of intensity. It wasn't just the volleyball, they noted. The North Koreans appeared to be no longer pumping water out of the tunnels used to test weapons, while vehicles and trailers near the entrance to these tunnels appeared to have been moved.

However, the exact status of the site was unclear. The 38 North analysts suggested two possible explanations: that the site has transitioned to a "standby” status, which allows some recreation time, or that Pyongyang was attempting to deceive the international community about the status of the site through a variety of methods, including staged volleyball games.

Apparent volleyball games could be seen at the three separate locations in the camp, with another net possibly being set up in another area. Satellite imagery has shown volleyball being played at the camp as far back as 2006, according to 38 North, but there has never been evidence of three concurrent games before.

Volleyball is considered to be one of the most popular sports in North Korea, along with basketball, soccer and table tennis. Notably, it's popular with both men and women. The North Korean women's volleyball team won bronze medals twice in the 1972 Olympics and the 1970 Women's World Championship, though they have rarely qualified for either event since.

North Korea had been widely expected to test a nuclear weapon last weekend, marking a day officially known as the “Day of the Sun” — the April 15 anniversary of the 1912 birth of Kim Il Sung, North Korea’s founder. In the end, no nuclear device was tested, but during a parade on Saturday the totalitarian regime did display a number of missiles that could theoretically reach the United States, and it made a failed bid to launch a ballistic missile the next morning.

Whether volleyball games have continued at the site since Sunday is unclear, though 38 North says it plans to release more up-to-date satellite imagery this week.

Kim Jong Un has tested nuclear weapons and ballistic missiles at an unprecedented rate since he came into power. Yet, the country is under some of the toughest sanctions ever. This is how the regime is able to funnel billions of dollars into its nuclear program. (Jason Aldag/The Washington Post)